The saddled sharpnosed puffer
C. valentini, the saddled or black-saddled, banded, striped, or Valentini's pufferfish, is the most often traded member of a genus known as the sharpnose pufferfishes or tobies. Sharpnose puffers are named so, because their snouts are pointed for selective feeding, and the gut contents of Canthigaster include varied small items of snipped off animal and plant material. This petite species grows only to 11 centimeters at the longest. or about 4 inches, and the species is most typically closer to 8 centimeters or 3 inches long.
C. valentini inhabits reef and lagoon habitats, as far west as the Indian Ocean coast of Africa, to as far east as the Tuamotos archipelago. This species is also recorded in mangrove environments, where it is associated with Rhizophora mangle, and may in fact be common in such habitat. Juvenile C. valentini are found only in particularly shallow and sheltered envirinments, whereas the older fish of the same species, have much broader preferences of habitat.
With their unusual looks and peculiar swimming mode, and their great personalities, the pufferfishes have found their way into the hearts of numerous aquarists. Other than the basal diodontids, or porcupine fishes, all pufferfishes belong to a subclade called Tetraodontidae. Tetraodontid puffers tend to have only a few external characters usetul to taxonomists, and a number of puffer genera in common use today, were formerly lumped into Tetraodon itself.
Puffers are closely related to the pelagic ocean sunfishes, or molids, the balistoids or triggerfishes, and the boxfishes or ostracoids. These fishes together comprise the tetraodontiform clade, which is marked by tendencies of morphological reduction, simplification, and loss of osteological elements. Puffers and molids share faces that are unusually modified to form a beak-like structure, whereas balistoids and boxfishes possess individual teeth protruding from sockets in their jaws. Pufferfishes also possess dermal spines, the distribution of which on the body, varies between the pufferfish species, and they are most developed in the diodontid puffer clade.
Puffers alone are able to inflate their bodies by a rapid intake of seawater, making themselves too large and difficultly shaped for predators to handle. Although only pufferfishes can inflate in this way, their ability to do so is because their ancestors had already lost their pelvis and pleural ribs. Some other tetraodontiforms can alter the external shape of their bodies, by moving their pelvis, although they do not inflate like the members of the diodontid and tetraodontid clade.
Most species of pufferfish are found in marine environments, but many species are present in estuaries and freshwaters. Marine pufferfishes are present at depths beyond 350 meters deep, and a few species of pufferfish are pelagic. But most marine pufferfish inhabit shallow, tropical seas, and these are the species exported for saltwater aquarium retail The appealing C. valentini is perhaps the most commonly traded of these pufferfishes today.
Unlike typical pufferfishes, Canthigaster have unusually narrow bodies, and fish of this genus are not as well able to self-inflate, as are more typical pufferfish species. Instead their defence relies on potent toxins that are present within their tissues. People have actually died after attempting to eat pufferfish, a phenomenon that is known medically as tetrodotoxin poisoning. In addition to the notorious tetrodotoxin, C. valentini possesses saxitoxins, and both are concentrated primarily in their skins and ovaries, but also in other tissues.
Canthigaster puffers have toxic eggs and larvae, and they remain poisonous to eat when they become adults. Their bright coloration in fact advertises their toxicity, informing predators that the puffer is dangerous to consume. Both juvenile and adult confidently swim over open sand, out in the open, being quite immune to predation. High toxicity arguably affords C. valentini its bold and inquisitive nature, which is beloved to so many aquarists. These diurnal fish practice courtship and spawning throughout the day, and there is no postpartum care of their eggs by either parent fish.
C. valentini have social and mating systems, in which both the female fish guard territories, and the males have harems of females. Female C. valentini chase away other females, whilst the territories of the mature males monopolise their visiting access to a few females. Because C. valentini is so dangeously toxic when eaten, another tetraodontiform species, the boxfish Paraluteres prionurus, has evolved to mimic C. valentini, in order to convince potential predators not to attack. Aquarists, too, might easily confuse these two species, which are so similar that the boxfish is sometimes mislabelled as the puffer. Some juvenile groupers also imitate the toxic C. valentini, and other members of its genus.
Because of its small size, some aquarists have attempted to maintain C. valentini in aquariums with live corals, and other sessile and motile benthic animals. This cannot be encouraged for the simple reason that wild C. valentini and its relatives, consume stony coral polyps as a part of their wide, natural diet. Although at least some of the tissues might be ingested incidentally, when nipping at organisms on living corals, there is no reason C. valentini should not be expected to purposefully bite corals themselves, and this is reported to occur in aquariums.
The gut contents of wild C. valentini demonstrate that its dietary spectrum is broad, including both plants and animals, and different Canthigaster species tend to consume the same categories of food, though they do so in differing proportions, so that the diet of one Canthigaster species bears relevance to that of another, without it matching. When it is compared to some other Cantnigaster puffers, C. valentini shows a particular preference towards nipping fleshy red macroalgae and tunicates, at least in Micronesia where members of the sharpnosed pufferfish guild show niche partitioning.
The organisms nipped by Canthigaster often have chemical defences of their own, which explains why these pufferfish merely nip a little off a growing animal or plant, and then moves along insteat of consuming them in bulk. Such feeding behavior in grazing and browsing animals, helps them by preventing poisoning by any one food source in great ammounts, wether the animals in question are sharpnosed pufferfish, or big, herbivorous land mammals such as elephants.
Members of the Canthigaster genus are known to nip at algae, big foraminifera, and sessile fauna, but also to consume motile benthic animals, such as gastropods, arthropods, and even echinoderms. Contrary to some claims, wild gut contents indicate the sharpnose puffers do not attack other fish in order to devour their scales or fins, a feeding behaviour reported in certain other tetraodontids. C. valentini are often housed with other fish species without incidents, it is true their territorial nature can cause some C. valentini be a little nippy to other species.
The breadth of their diet makes Canthigaster puffers easy to feed in the home aquarium. Foods of both animal and vegetable origin must be given to these fishes, and their diet ought to be varied for the sake of their health. C. valentini are territorial, with their territories centered upon a crevice in a hard substrate, and as might be expected, this species can be pugnacious to their own and other Canthigaster species. Maintaining this species in groups is definitely not recommended.
C. valentini are a small pufferfish suited to a 30 gallon aquarium, making then easier to accommodate than larger puffer species, which might be purchased young by the unsuspecting aquarist, then subsequently outgrow their tanks. But a lot of information about this species with other tankmates is contradictory, which is partly because of personality and habit variation between the individuals, and because their territoriality increases with age, and it is females that are most guarded, at least towards their own or similar species.